Using Nitrogen In Central Air Conditioning Installation

There are some parts of the world where a functioning air conditioning system is the only way to stay remotely comfortable in the summer. Though living without such a system is possible, as it has been for thousands of years in many parts of the world, modern conveniences and comforts have allowed generations people an unprecedented degree of comfort during the summer season.

While drinking enough water and staying out of the sun are important and indeed very comfortable for people living in a sweltering climate, the fact is that air conditioning really does make the summer a lot easier to handle no matter what kind of health you’re in. And if your state of health is fragile for one reason or another, a good air conditioning system can be vital for staying healthy in the summer heat.

Hire An Experienced AC Installation Contractor

But there are a number of problems associated with improper installation of air conditioning systems, the least of which is setting them up, typically the work of a technician or team of technicians that is trained and ideally certified to work on residential HVAC systems. A major step in the installation of an air conditioning system is the nitrogen purge. This purge works by pumping a full-fledged infusion of nitrogen into the air conditioning system to prepare it to run chilled air through its pipes and vents.

The nitrogen flows through copper tubing during brazing. Flowing nitrogen through an air conditioning system’s copper tubing is essential. Because oxygen tends to fuse with copper to cause copper oxidation, the pipes tend to crack and flake. While outwardly this seems to be merely a cosmetic problem, inside the pipes, the black flakes and grit are capable of plugging up essential systems and meters in the air conditioning system, typically at the worst possible times.

Prevents Copper Oxidation

Flowing dry nitrogen through the copper tubing of an air conditioning system will prevent oxidization because it is inert, that is non-reactive to the copper. However, it will displace the oxygen that would otherwise transform the inside of the pipe into a flaky copper oxide. The nitrogen typically enters the systems through a device called a Schrader valve once the core of the pipe is removed, though other system openings for this procedure do exist.


From there a hose from the nitrogen cylinder connects to the system. The cylinder is universally connected to a regulator, also called a flow control valve. The goal is to use a low volume of nitrogen piped in under low pressure to displace the oxygen. Most HVAC technicians start with 2-3 CFH or 1.5 to PSI. Other technicians set pressure until they feel a slight but noticeable flow on their skin when placed near the exit point.

Watch The Flow Rate

An excessive flow rate is generally a bad thing. A high flow rate of nitrogen into copper tubing tends to cool the tube too much to allow for efficient brazing heat to prepare the tubes to flow air. Excessive pressure from the nitrogen can also build up in the tubes and severely lower the rate of braze alloy penetration.

So remember, using nitrogen to purge the refrigerant lines is a critical part of a professional air conditioning installation.